PEL: Add string accessors to MTMS class

This class is used by a few other classes, so make it easier to get
data out of it.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I2feb4b83a09e6cb6056c9f1a903ca55e8cacf2ae
diff --git a/extensions/openpower-pels/failing_mtms.hpp b/extensions/openpower-pels/failing_mtms.hpp
index 209eaa9..bbf0b2a 100644
--- a/extensions/openpower-pels/failing_mtms.hpp
+++ b/extensions/openpower-pels/failing_mtms.hpp
@@ -66,14 +66,20 @@
      *
      * @return std::string the MTM
      */
-    std::string getMachineTypeModel();
+    std::string getMachineTypeModel() const
+    {
+        return _mtms.machineTypeAndModel();
+    }
 
     /**
      * @brief Returns the machine serial number as a string
      *
      * @return std::string the serial number
      */
-    std::string getMachineSerialNumber();
+    std::string getMachineSerialNumber() const
+    {
+        return _mtms.machineSerialNumber();
+    }
 
   private:
     /**